This invention is in the field of extraction and refining of essential oils from biological material. The invention relates generally to the closed loop extraction of oils from plant matter. The invention also generally relates to the purification of extracted oil to remove unwanted compounds extracted concurrently with the oil, such as waxes.
Oils derived from plant matter are desirable in a wide variety of industries and applications. For example, the fragrance and perfume industries require a variety of essential oils for fragrance compounds. The food industry also extracts specific taste-affecting compounds and flavors from plants. Extraction has been utilized to extract a wide array of compounds such as medicinals, lipids, carotenes, alkaloids, tocopherols, and tocotrienols. More recently with the decriminalization of medical cannabis, and in some states legalization of recreational cannabis, extraction of pharmacologically active compounds from marijuana, such as tetrahydrocannabinol (THC) and cannabidiol (CBD), have received increased attention.
Currently, the most common methods for the extraction of oils from plant materials are solvent extraction and supercritical fluid extraction (SFE). SFE uses supercritical fluids to selectively remove extracts from solids, semisolids and liquids. Both solvent extraction and SFE have been developed using a variety of solvents, for example, carbon dioxide, propane, butane, ethane, ethylene, propane, propylene, cyclohexane, isopropanol, benzene, toluene, p-xylene, chlorotrifluoromethane, trichlorofluoromethane, ammonia and water. Each specific solvent has certain advantages and disadvantages and solvents tend to be selected based on the equipment being used, chemistry of the extract and plant material, safety, government regulations, and cost.
Current methods of SFE and solvent extraction both have disadvantages in the cost or complexity of the equipment required. For example, SFE can involve heating the solvent to tight-tolerance temperatures and pressuring to high pressures, which is both costly and a safety concern. While solvent extraction is often performed at lower temperatures and pressures, current methods often risk exposure to the solvent material which can be toxic, explosive or carcinogenic. Additionally, solvent may be lost between non-interconnected components. Current solvent extraction methods also have selectivity problems, as they often extract additional compounds, such as waxes, which are undesirable in the oil product.
As can be seen by the foregoing, there remains a need in the art for closed loop solvent extraction methods and systems for the extraction of oils from plant material which provide reduced costs, higher safety and increased purification and removal of waxes from the extracted oil.